1. Field of the Invention
The present invention relates to a ski brake associated with an alpine ski binding, more particularly a heel binding.
2. Description of Background and Relevant Information
Ski brakes are apparatus mounted on a ski which are adapted to prevent the ski from sliding down the slope when the ski is freed, as a result of the release of a safety binding during a fall. Ski brakes which are now commonly utilized in skiing generally comprise an elastically biased mechanism which comprises, on the exterior of the ski and on each side thereof, a pivoting spade or protrusion. This protrusion is adapted to engage in the snow when the ski brake is in the active braking position. Each braking protrusion is rotatably movable around an axis which is substantially transverse with respect to the ski. The ski brake furthermore comprises a control element, such as a pedal, which is activated by the boot of the skier, when inserting the boot, in a manner so as to make the protrusions pivot and to make them pass from the active braking position to an inactive position in which the protrusions are substantially lifted above the upper surface of the ski. If desired the pedal can then make the protrusions pass into a retracted position in which they are brought towards one another horizontally, in the direction of the longitudinal median plane of the ski, on both sides of the body of the heel binding, such that the ski brake leaves the skis as unencumbered as possible during skiing.
The passage of the protrusions from the active braking position to the inactive position occurs against the force of elastic return means. These return means have an energy which progressively increases from the active braking position to the inactive position. This energy is translated, to the projections, by a force or a rotational moment of the projections which tend to make them pivot downwardly, and, on the pedal, by a force or rotational moment which biases the pedal upwardly. The elastic return means most commonly utilized comprise one or more traction springs, in compression or torsion, a deformable energy buckle, etc.
In these ski brakes, the elastic return means are autonomous and independent of the rest of the safety binding itself, i.e., of the heel binding. Generally the base of the brake is affixed to the ski and the ski brake is separated from the heel binding, i.e., it does not accompany it in its longitudinal movements, during length adjustment or retraction during insertion of the boot.
The principal inconvenience of these ski brakes is that in the position where the boot is inserted, which corresponds to the inactive position of the protrusions, the control pedal which senses the presence of the boot, exerts a vertical force upwardly on the sole of the boot at the linkage between the boot and the jaw of the heel binding. This upward force becomes a parasitic force at this location because it tends to lift the jaw even at rest. It is possible to diminish the intensity of this parasitic force, for example, with an "elbow" construction, but the more that this force is diminished the less likely it is that the brake will release in the case of a fall.
Other ski brakes are known in which the elastic return means of the protrusions in the active braking position are common with the energization means of the heel binding itself. The most common construction consists of utilizing the energy of one or more return springs of the heel binding. In this respect, French patent No. 2,412,324 describes a ski brake in which the movement of the protrusions is directly linked to the movement of the heel binding, and the control element of the ski brake is the body of the heel binding itself. Furthermore, French patent No. 2,467,611 describes a ski brake in which the control pedal of the brake is mechanically connected to the body of the heel binding.
Ski brakes of these types have the advantage that when the boot is inserted there is practically no accumulated energy in the brake such that the control pedal exerts only a very weak force under the sole and there is practically no parasitic energy which is created which appears at the location of contact between the boot and the jaw of the heel binding. The ski brake according to French patent No. 2,412,324 furthermore has the advantage of not having a brake pedal. However, this construction is complex because the amplitude of the return movement of the binding is relatively small (on the order of several millimeters), and the rotational movement of the projections is by way of comparison relatively substantial (close to 90.degree.). The transmission between these two movements is thus delicate. Another disadvantage of this ski brake is that the energy of the brake depends directly on the return energy of the binding. In other words, if one changes the return energy springs, one modifies also the energy of the brake.
These disadvantages likewise are found in the ski brake of French patent No. 2,467,611. This ski brake furthermore has the disadvantage that the movement of the heel binding and the movement of the control pedal are directly connected on the mechanical plane and yet both are separately controlled by the movement of the boot. There is thus an additional problem of synchronizing different movements with a substantial risk of floating of the heel binding or of the pedal in the position where the boot is inserted.